1. Field of the Invention
The present invention relates to an improved process and a novel catalyst composition for upgrading catalytically cracked liquid hydrocarbons containing sulfur impurities, olefinic components and other unsaturated components.
2. Description of the Prior Art
Catalytically cracked liquid hydrocarbons boiling in the gasoline range often contain substantial proportions of sulfur impurities. Such sulfur impurities require removal, usually by hydrotreating, in order to comply with products specifications and/or to comply with environmental regulations. The forthcoming environmental regulations established by the Clean Air Act (complex model) will require gasoline to have more stringent low levels of sulfur impurities.
While hydrodesulfurization processes and catalysts are commonly utilized to remove sulfur impurities from catalytically cracked liquid hydrocarbons, the hydrotreatment also causes a reduction in the olefin and other unsaturated hydrocarbon content of the liquid hydrocarbons which in turn reduces the octane number thereof. As the degree of desulfurization increases, the octane number of the catalytically cracked liquid hydrocarbons decreases. In addition, the use of a hydrodesulfurization process to remove sulfur impurities from catalytically cracked liquid hydrocarbons significantly reduces the volume of the liquid hydrocarbons remaining after the treatment.
Thus, there are needs for improved processes and/or catalysts for upgrading catalytically cracked liquid hydrocarbons whereby the hydrodesulfurization and liquid yield of the liquid hydrocarbons are enhanced as compared to prior processes while the octane number of the upgraded liquid hydrocarbons is substantially maintained.